Carphone plans to revise its salary "top-up" structure

Graduate James Edgerton said the firm had clawed back "top up" money which was orginally paid to him to ensure his starting salary met the wage threshold.

Once he was earning enough through commission, he said the company took the money back from his total salary.

Carphone said it was taking steps to remove this "grey area".

'Completely unfair'

Mr Edgerton, a graduate of business studies, started work as a sales consultant at a Carphone Warehouse outlet in Bristol.

Under its guaranteed minimum earnings scheme, his basic annual salary for a 45-hour working week was �8,250, less than the minimum wage, topped up by commission.

Because in his first month he was training, he earned no commission, but Carphone topped up his salary to the tune of �200 to take it up to the minimum wage.

But the following month, when he was finally earning commission, he discovered this original �200 had been taken out of his total pay packet.

"It is completely unfair that when someone has a good month they don't get paid any more," Mr Edgerton said.

After contacting the Department of Trade and Industry's National Minimum Wage unit, the issue was resolved with the firm.

'Small technicality'

In a statement, Carphone Warehouse said: "It is impossible to earn less that the national minimum wage at The Carphone Warehouse.

"The national minimum wage is �877 per month. The Carphone Warehouse has it's own minimum earnings of �1,000 per month, 13% higher than the national minimum wage.

"In fact the average sales consultant at The Carphone Warehouse earns over �14,000 per annum, 40% higher than the minimum wage."

A spokeswoman for the company told BBC News Online that Carphone Warehouse was currently working with the National Minimum Wage compliance team to clear up a "small technicality" regarding its pay top up structure.